'Assassin' cells home in on HIV

Monday, 10 November 2008

Cells have been successfully engineered in the laboratory to overcome one of HIV's most effective defence mechanisms, say researchers.

The immune system cells, created by UK and US scientists, can lock on to HIV, even after it has mutated to throw them off the scent.

It is hoped the Nature Medicine study could lead to a more effective way of tackling HIV infection.

Tests on people with advanced HIV may start next year.

Most viruses can be "cleared" by the body's own defences, partly due to cells called "killer T-cells", which learn to recognise the intruder and eliminate it.

However, HIV's power stems from its ability to mutate rapidly to evade detection and destruction.

The project underway at the Universities of Cardiff and Pennsylvania, in partnership with an Oxford-based biotech company, involves the creation "souped-up" T-cells with the ability to recognise and attack more of these mutated forms.

To do this, the scientists attach extra versions of the "T-cell receptor", the part of the cell responsible for scanning and removing infected cells, which have been preset to identify various HIV mutations.

In laboratory studies, the modified T-cells were able to destroy HIV cells in a laboratory cell culture.

'Crippled virus'

Professor Andy Sewell, from Cardiff, said that he hoped that in humans, the effect would be equally devastating to the virus.

"In the face of our engineered assassin cells, the virus will either die or be forced to change its disguises again, weakening itself along the way.

"We'd prefer the first option but I suspect we'll see the latter. Even if we do only cripple the virus, this will still be a good outcome, as it is likely to become a much slower target and be easier to pick off.

"Forcing the virus to a weaker state would likely reduce its capacity to transmit within the population and may help slow or even prevent the onset of AIDS in individuals."

Dr Ade Fakoya, from the International HIV/AIDS Alliance, said that the work essentially amounted to an "enhanced detection" system to detect HIV as it lay hidden in cells.

However, he warned that it might not be a suitable strategy for everyone with HIV.

"It is very interesting basic research and as such really does contribute to our knowledge of what might work as a immunological treatment strategy. It is early days in the search for an effective immune based treatment for HIV.

One limitation however is that the immunological assassins generated by this technology are done using a specific part of the receptor of the active cells.

"The genetic make up of these receptors do vary with different racial populations."

Garry Brough, from the HIV charity Terrence Higgins Trust, described the research as "potentially very good news for people living with HIV".

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